A lithium ion secondary battery is known as an advantageous secondary battery which is able to give a high voltage of about 4 volts and a high discharge capacity. As the positive electrode active material of the lithium ion secondary battery, LiMn.sub.2 O.sub.4 having a spinel crystal structure, as well as LiMnO.sub.2, LiCoO.sub.2, LiCo.sub.1-x Ni.sub.x O.sub.2 or LiNiO.sub.2 which has a rock salt crystal structure have been generally employed. The LiCoO.sub.2 having the rock salt crystal structure shows higher voltage and higher discharge capacity than other oxides and therefore is advantageous. However, the LiCoO.sub.2 has such drawbacks that cobalt is economically disadvantageous and less available than other metals, and moreover may cause environmental pollution if battery wastes containing the lithium cobalt oxide are left outside.
Japanese Patent Provisional Publication H3(1991)-147276 proposes a lithium ion secondary battery using LiMn.sub.2 O.sub.4 of the spinel crystal structure as the material for its positive electrode, that is, cathode. Manganese is economically advantageous and easily available, and moreover scarcely causes environmental pollution. However, LiMn.sub.2 O.sub.4 gives a charge capacity (corresponding to amount of releasable lithium ions) per unit volume less than LiCoO.sub.2 by 10 to 20%. This means that if the LiMn.sub.2 O.sub.4 is combined with a negative electrode active material of high capacity to prepare a secondary battery, the volume of the LiMn.sub.2 O.sub.4 (namely, positive electrode active material) to be used should be increased so as to balance its capacity with the high capacity of the negative electrode active material. As a result, the amount of the negative electrode active material encased in a container of a battery should be reduced, and then the battery capacity lowers.
Japanese Patent Provisional Publication H4(1992)-147573 describes a lithium ion secondary battery using Li.sub.1+x Mn.sub.2 O.sub.4 (x&gt;0) as the positive electrode active material precursor in combination with a negative electrode active material precursor such as carbonaceous material. The combination of a positive electrode active material precursor and a negative electrode active material precursor in a container of a battery is electrochemically converted into a positive electrode active material-negative electrode active material combination by electrically charging thus prepared battery so as to release a lithium ion from the positive electrode active material precursor and intercalate the released lithium ion into the negative electrode active material precursor in the container.
U.S. Pat. No. 4,002,492 describes a lithium alloy as a negative electrode active material showing an increased electric capacity per unit volume. The use of a lithium alloy as a negative electrode active material, however, may cause a specific trouble, that is, production of lithium metal dendrite on the surface of the lithium alloy (i.e., negative electrode active material) in the course of charge-discharge cycle (namely, intercalation and release of lithium) with a high current density. The produced lithium metal dendrite may be in contact with a positive electrode and may produce an internal short circuit. Otherwise, the lithium metal dendrite may react with an electrolytic solution to deteriorate the cycle characteristics of the battery.
Japanese Patent Provisional Publication No. 60-86760 describes that the production of lithium metal dendrite can be obviated by replacing aluminum which is used as a binder of lithium metal with an alloy of aluminum and such other metal as magnesium, boron or gallium.
Japanese Patent Publication (examined) No. H7-114124 describes that a metal alloy negative electrode giving less lithium metal dendrite can be produced by forming an alloy of lithium metal with other metal fusible with lithium metal in the presence of a sub-metal which does not form an alloy with lithium.
The lithium metal alloy of the prior art, however, still is not completely free from the production of lithium metal dendrite on the negative electrode. Particularly, when the charge-discharge cycle undergoes with a high electric current density or reaches overcharge, the lithium metal dendrite is apt to appear.